Safety Factor, is a multiplier applied to the calculated maximum load to which a component or assembly will be subjected. Thus, by effectively "over engineering" the design by strengthening components etc
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Aerospace engineering where safety factors can be as low as 1.10 or 1.25 (in extreme cases like unmanned vehicles) or more typically 1.50, are relatively low because the costs associated with structural weight are so high. This low safety factor is why Aerospace parts and materials are subject to much more stringent testing and quality control
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One can easily design an Aircraft with for example, a safety factor of 5.00
.. PAS loads would be amazingly low
.. fuel consumption extremely high and range well below needs
. Probably impractical
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The 380 tests being so close to the design objective of 1.50 is rather impressive if one thinks about it
.. its just a pity it is slightly below target rather than on or just above ,,,,